You could have a talk with your local feed store. They should have some knowledge and carry whats needed or can get it. They wouldn't be in business if they didn't know something about what they were doing. There's water soluble vitamins, electrolytes, antibiotics, feed supplements and medicated feeds as a preventative and for treatments. none are cure-alls. Read the labels
Here's some what of a guide that gives explanations.
http://msucares.com/poultry/feeds/bwqfeed.html#vita